Determinants of Birth‐weight in the New Territories of Hong Kong

Abstract

Weights of babies born in the Prince of Wales Hospital, Hong Kong, in its first 2 years of operation were studied, and compared with previous reports. Birth-weight in Hong Kong appears to have increased significantly in recent years. The method of data collection effects reference standards of birth-weight. The effect of different methods of data collection and statistical treatment of data for providing reference standards of birth-weight are discussed. In this series average birth-weight increased by 6.8 g per year of maternal age, 13.3 g per cm of maternal height, 42.5 g per previous baby and 104.9 g per week of gestational age; males were 110 g heavier than females. The effects of parity became significant at 35 weeks, and that of maternal age and height at 36 weeks; the effect of fetal sex was significant from 38 weeks onwards.

Customized birth weight: coefficients and validation of models in a UK population

“…The findings of this study confirm the strong association between birth weight and both maternal and fetal factors1–14. In our models gestational age, maternal height, weight, parity, ethnicity and the baby's gender all had significant influence on the birth weight.…”

“…Statistical models have been developed that incorporate maternal and fetal factors to calculate a ‘customized’ or ‘individualized’ optimal weight ‘at term’ for a given pregnancy1, 2. Formulae describing the optimal birth weight at term have now been produced for homogeneous or mixed ethnic populations in several countries3–14. The optimal birth weight at term has been combined with a standard proportional growth curve to describe how a fetus would be expected to reach that endpoint at any gestational age in an uncomplicated pregnancy1, 2.…”

A Test of Agreement of Customised Birthweight Models

“…Studies were excluded if they were not written in English (as they were unlikely to report a White‐European coefficient). Nineteen studies were identified that reported new CBMs; seven were subsequently excluded for reasons of: no White‐European coefficient, required predictors missing or using substantially different methodologies …”

Customised birthweight: Coefficients for an Australian population and validation of the model

“…8,10,11 The  model presents an overall mean value, and the formula allows this mean value to be adjusted according to each parameter. Such a model is intuitively easier to understand and use, but some precision is lost because continuous measurements are arbitrarily reduced into groups.…”

“…Wilcox 9 took a similar approach, but used Multiple Regression to model birthweight. Both models used a least squares approach, and were subsequently found to be applicable among the Chinese population in Hong Kong, 10 and mixed ethnic populations in the UK, [11][12][13] Sweden 14 and New Zealand. 15 The terms customised growth chart and customised birthweight were used to represent this reference weight.…”